You bestow the subject with the ability to use a single type of weapon he is not proficient in as if he were proficient with that weapon. The weapon can be any type, including an exotic weapon, but the subject of the spell must be holding the weapon* when you cast it.

*Editor's Note: The original text is, "the subject of the spell must be holding the spell when you cast it." We believe the original text should have been "...holding the weapon..." Official errata has not been released for this but we have corrected it anyway.